Electric power systems are widely used in electrically powered machines to provide power for propulsion and other operations. Typically, an electric power system includes a generator coupled to an engine to convert mechanical power to electrical power. The electric power system also includes multiple inverter units individually connected to the generator for converting an Alternating Current (AC) input from the generator into a Direct Current (DC) internal to a capacitor bank and back to an Alternating Current (AC) output for use by the components of the machine, for example machine propelling motors. Further, the electric power system may be configured to provide a DC input or output for use by the components of the machine. The inverter units may be interconnected to each other such that two or more of the inverter units may collectively supply the AC or DC output to one or more such components of the machine.
In some applications, the inverter units are placed at distant locations on the machine, and are electrically connected to each other using connection cables. Due to high impedance of the connection cables, the inverter units are susceptible to electric resonance, which may lead to increase in power losses. The placement of the inverter units at the distant locations is also undesirable for a variety of other reasons, such as lack of space on the machine and high servicing and/or maintenance time.
U.S. patent application publication number 2014/0361613 (the '613 publication) discloses a system configured to reduce the amplitude of reactive current present on a DC bus shared by multiple inverters. The start of the switching period for the modulation routines of each inverter is synchronized, and a carrier phase angle is determined for a carrier signal within each of the inverters. The modulation routine of each inverter generates a reactive current on the shared DC bus. By controlling the carrier phase angle for each inverter, the reactive current of a first inverter may be generated at a phase angle that is offset from the phase angle of the reactive current generated by a second inverter. As a result, the reactive current from the first inverter cancels at least a portion of the reactive current from the second inverter, reducing the total reactive current present on the DC bus. Notwithstanding the above, the multiple inverters of the '613 publication may be susceptible to electric resonance when placed in a single housing.